The present invention relates to a coil unit, a wireless power feeding device, a wireless power receiving device, and a wireless power transmission device.
Recent years have seen growing attention in the fields of electric vehicles and mobile devices to wireless power transmission technologies that wirelessly supply electric power from external sources without use of power cables. When such wireless power transmission technologies are used for chargers that require large power transmission, such as those used in electric vehicles, a large current needs to be passed through the power transmitting coil, leading to an increase in leakage flux. This may cause adverse effects on nearby electronics, such as electromagnetic interference.
To address this problem, for example, Patent Reference 1 discloses a contactless power feeding device whose primary and secondary sides each include the following components arranged in the order given below, as viewed from the air gap: a coil with a flat structure wound in a spiral shape, a ferrite core having a flat planar shape, and an aluminum plate having a flat planar shape. The aluminum plate blocks exposure of leakage flux to the outside.